If God foreknows that a man named Saul will persecute Jesus' followers, but later he will repent, turn around, and then become a zealous Christian himself--does God's knowledge of Saul's future actions mean that Saul necessarily carries out such activities?
While it's conceptually possible that we could say Saul will necessarily persecute Christians, but subsequently become a Christian himself--Boethius shows that we cannot rightly conclude God will cause Saul to persecute Christians, etc. For if I behold a man walking or sitting, it does not mean that the man's walking or sitting is necessary in a simple sense (i.e., it does not mean that the man's sitting or walking is caused by my visual activities or that the man's ambulatory movements cannot not happen).
If I watch an oval-track race on a hot Sunday afternoon, I do not cause the cars to travel incessantly around the track by watching the race. Similarly, even though God beholds certain future events, it seems that we cannot justly infer that His foreknowledge causes Pharaoh to act recalcitrantly or influences Peter to deny Jesus. Some might say that both Peter and Pharaoh still have the power to bring about different outcomes although God knows that they will not: He does not cause such events.
Boethius' explanation works beautifully in some ways; however, I disagree with his delineation of God's atemporality. But the distinction between conditional and simple necessity is helpful.
On the other hand, it's also difficult to understand how Boethius' explanation preserves libertarian free will. I have a similar criticism of Calvin's account.
See Boethius' work The Consolation of Philosophy 5.